Comment 317 for bug 125970

To be honest, I don't know. They just state they have Cairo graphics backend for GTK port, as they state here (under Shared Code Modules, it seems they are using it for image and SVG rendering):

http://trac.webkit.org/wiki/HackingGtk

For me, with the newest NVIDIA drivers for Linux, problem doesn't exist if the fixed element is an image(like fixed background). If the fixed element contains some text, it starts to get laggy, and if I resize the page (doesn't matter if I enlarge or shrink it) the scrolling is very laggy.

The problem on Linux starts here:

- resize the page: everything will start working a lot slower
- resize text only: everything is ok
- resizing takes a lot of time (few secs to resize Wikipedia once to a certain level, where Opera can do 7-8 resizes a second to make it look smooth). It seems Firefox doesn't reuse the fonts it loaded, it just loads them on every resize until they'll get cached in memory.

I think the worst problem exists with fonts and Pango backend - Firefox 2 behaved this way, using MOZ_DISABLE_PANGO=1 helped A LOT. But there is no way of disabling this in FF3. I believe this is the source of other bugs (like this one).